com.fluxtion.api.event.Signal Maven / Gradle / Ivy

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/*
 * Copyright (c) 2020, V12 Technology Ltd.
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the Server Side Public License, version 1,
 * as published by MongoDB, Inc.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * Server Side Public License for more details.
 *
 * You should have received a copy of the Server Side Public License
 * along with this program.  If not, see 
 * .
 */
package com.fluxtion.api.event;

/**
 * A notification signal is an event that facilitates publishing control signals to event
 * handlers. Signal remove the need to define bespoke control events by
 * using a named signal and filtering .
 * 

 *
 * The {@link  Signal#filterString} filters events a receiver will
 * process. The generated SEP provide all filtering logic within the generated
 * dispatch code. A node marks a method with a filtered EventHandler annotation
 * as shown:
 * 
 *  * Sending
 * StaticEventProcessor processor;

 * processor.onEvent(new Signall{@literal >}("someKey", new ConcurrentLinkedQueue<>(List.of("1","2","3","4", "5", "6"))));
 * 
 * Receiving
 * {@literal @}EventHandler(filterString = "filterString")

 * public void controlMethod(Signal publishSignal){

 *     //signal processing logic

 * }

 * 
 *
 * Using the propagate=false will ensure the event is consumed by the signal
 * handler. Swallowing an event prevents a control signal from executing an
 * event chain for any dependent nodes of the event processor:
 * 

 * 
 *  *{@literal @}EventHandler(filterString = "filterString", propagate = false)
 * 
 *
 * The Signal also provides an optional value the receiver can
 * accessed via {@link #getValue() }.
 *
 * @author Greg Higgins ([email protected])
 */
public class Signal implements Event{
    
    private String filterString;
    private T value;

    public Signal() {
    }
    
    public Signal(String filterString) {
        this(filterString, null);
    }
    
    public Signal(Enum enumFilter){
        this(enumFilter.name());
    }

    public Signal(String filterString, T value) {
        this.filterString = filterString;
        this.value = value;
    }

    public T getValue() {
        return value;
    }


    public void setValue(T value) {
        this.value = value;
    }

    public String getFilterString() {
        return filterString;
    }

    public void setFilterString(String filterString) {
        this.filterString = filterString;
    }
    
    @Override
    public String filterString() {
        return filterString;
    }

    @Override
    public String toString() {
        return "Signal: {" + "filterString: " + filterString + ", value: " + value + '}';
    }  
    
}